I have a Supermicro rack-mount case that has four proprietary, hot-swap 80-mm 4-pin fans (model FAN-044) that snap into special holders inside the case.

I want to re-use an old Gigabyte mobo in this case so you already know the issue - the mobo has 3-pin fan headers and only two available.

I've researched those 5.25" bay insert-type fan controllers but the handful that control PWM-type fans only have one or two headers available for the 4-pin types, so I'm looking at one that will control four fans with 3-pin headers.

I see that there are 4-pin to 3-pin conversion sockets available. What has been your experience with this type of situation? Do you think that these fans work properly if plugged into 3-pin headers, or am I just headed for trouble?

Replacing the fans in the case with 3-pin 80mm types is not possible as the case holders are designed only to accept the FAN-044 design.

Thanks,Ed

Scott

Post subject: Re: 4-pin PWM fans

Posted: Sat May 16, 2009 10:23 am

Site Admin

Joined: Sun Feb 04, 2007 11:44 amPosts: 6122

In my experience there is almost no such thing as a "proprietary" fan, only standard fans mounted in proprietary brackets or enclosures. When replacing these, I've never had a problem simply removing the existing industry standard fan from the proprietary bracket or enclosure, and replacing it with a new one.

So while you probably *could* replace the fans if you wanted to, that would only be necessary if they had failed. If they are working, then you don't need to replace them since 4-wire PWM fans are backwards compatible with 3-wire fan connections, and vice versa. In other words you can plug 4-wire fans directly into 3-wire fan headers, or 3-wire fans into 4-wire headers. In either case the 4th (blue PWM signal) wire simply won't be connected, resulting in standard 3-wire fan operation. Scott.

twosteppin_ed

Post subject: Re: 4-pin PWM fans

Posted: Sat May 16, 2009 10:35 am

Joined: Sat Apr 26, 2008 12:14 amPosts: 64Location: Port Orchard, WA

Scott,

That's GREAT news! Thank you for this info and your quick response.

Ed

twosteppin_ed

Post subject: Re: 4-pin PWM fans

Posted: Sat May 16, 2009 11:46 am

Joined: Sat Apr 26, 2008 12:14 amPosts: 64Location: Port Orchard, WA

Hi Scott,

The 5.25" bay-mount fan controller I am looking at varies fan RPM by varying the output voltage to the fans.

In this case of 4-wire PWM fans connected to 3-wire headers on this controller, varying the voltages via the controls on the controller will result in successfully varying the fan speeds without damage to the fans, right? Just wanted to make sure my assumption is correct before I dive in.

Thanks again,Ed

Scott

Post subject: Re: 4-pin PWM fans

Posted: Sat May 16, 2009 11:50 am

Site Admin

Joined: Sun Feb 04, 2007 11:44 amPosts: 6122

4-wire fans are just 3-wire fans with the extra option of PWM speed control. No damage will occur when reducing the voltage. Scott.

I once got a fan out of an old 3com switch (sounded like a cheap helicopter!) and the pins were reversed, so when I cut a hole in the case and replaced with a 92mm fan I blew the fan clean up!!!! So just check the voltage of the parts and match. The gigabyte MB will have standard pins but the old fans might be Reversed.

I prefer PWM fans anyway as they speed up and down depending on the heat thrown out by the CPU and chipset (I believe).

twosteppin_ed

Post subject: Re: 4-pin PWM fans

Posted: Thu Jul 09, 2009 8:02 pm

Joined: Sat Apr 26, 2008 12:14 amPosts: 64Location: Port Orchard, WA

Hi David,

I bypassed using the fan headers on the mobo altogether and hooked the 4 PWM fans supplied with the case up to a separate fan controller:

It works great! I can even adjust the fan RPMs so precisely that they all run at the exact same speed, resulting in a smooth, synchronized sound - much like where you precisely adjust multiple prop engines on aircraft to eliminate the "beating" sound that annoys passengers, LOL!

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